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PostPosted: Wed Jun 25, 2014 1:32 pm 
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completely agree ross , hence me giving up on the 4 sq test .


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PostPosted: Wed Jun 25, 2014 3:39 pm 
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Dear Rob,

If you have a wideband lambda sensor hooked up, you can do a test to determine the injector "dead" time:- holding it at a constant medium to high rpm, run it at 2 squirts per cycle and note the lambda reading. Switch to a different numbers of squirts per cycle (e.g. 1) and note whether the lambda reading changes. Adjust your injector deadtime until swapping the number of squirts per cycle makes no difference - this is the point where the deadtime must be correct. Once you have deternmined this for your setup, don't alter it.

If you wish, you can then adjust your "Reqfuel" to then let your fuelling table have a wide spread of values to make tuning adjustments easier. At the end of the day, the two are simply multiplied together anyway, so absolute numbers aren't important.

From your post last October, correct deadtime was 3.3-2.2 = 1.1mS. This also tells you that any pulsewidth below 3.3mS will deliver no fuel and that the minimum amount of fuel delivered is always at least 2.2mS worth. No doubt the resistors and the voltage will slightly alter these times.

You'll want to adjust the gas pressure (or jet size) so that an acceptable idle (i.e. minimum usage) can be achieved with just over 2.2mS of fuel (assuming 1 squirt per cycle) and then look to see whether the highest rpm achievable still allows enough time for the injector to deliver enough fuel at this peak demand level.

kind regards
Marek


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PostPosted: Wed Jun 25, 2014 8:55 pm 
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That's a clever technique, I like that.

I guess the 'dead time' from published opening - closing times is a reasonable approximation, although it does assume the gubbins acceleration is the same in either direction. Be interesting to see if it still holds true for clonky gas injectors. I wonder how carefully the return springs are selected - must say I've no idea if the different impedance coil variations of common types are sprung differently.

Still got my money on extended opening time due to resistor drive ... and I reckon that will perhaps extend closing time too, as the standing current at off-time will be higher than the 'hold' part of peak-n-hold. Will that show up as a small 'dead time' but rather non-linear injector curve in Megasquirt terms? Interesting stuff.

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PostPosted: Thu Jun 26, 2014 5:34 am 
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hi marek , thank you for this , it validates my method :-)

the reason I was experimenting with the 4 sq was to do what you are describing adjusting the dead time until the engine replicated the 2sq running ,and use that to determine the correct dead time .it didn't work becaue the inj are too big for that tiny pulse width on 4sq .

I had already adjusted the gas pressure to give the highest pressure compatible with smooth 1k rpm tickover ,this worked out to be 16 psi .

I am using a tech edge wide band ,this is connected to the msqt and is used for the live closed loop mapping(autotune) and ego running correction .

I am at 4ms at idle now .and its nice and smooth , I have a very tiny tip in accel stumble I want to work on .maybe with the accel map map .at the moment I have only used the accel throttle pos map.

I may try the 1 squ , but im on a bit of a time critical process where I have to have it reliable for a airport pickup on sunday ,as my girlfriend flies in from prague !

if I can get it smooth ,and repeatable and starting well,i still have to sort cranking pw , not really sure which way to go there my instinct is saying something like 1.5 times idle pw , then I will use it and refine as I go .

thanks
robert

marek wrote:
Dear Rob,

If you have a wideband lambda sensor hooked up, you can do a test to determine the injector "dead" time:- holding it at a constant medium to high rpm, run it at 2 squirts per cycle and note the lambda reading. Switch to a different numbers of squirts per cycle (e.g. 1) and note whether the lambda reading changes. Adjust your injector deadtime until swapping the number of squirts per cycle makes no difference - this is the point where the deadtime must be correct. Once you have deternmined this for your setup, don't alter it.

If you wish, you can then adjust your "Reqfuel" to then let your fuelling table have a wide spread of values to make tuning adjustments easier. At the end of the day, the two are simply multiplied together anyway, so absolute numbers aren't important.

From your post last October, correct deadtime was 3.3-2.2 = 1.1mS. This also tells you that any pulsewidth below 3.3mS will deliver no fuel and that the minimum amount of fuel delivered is always at least 2.2mS worth. No doubt the resistors and the voltage will slightly alter these times.

You'll want to adjust the gas pressure (or jet size) so that an acceptable idle (i.e. minimum usage) can be achieved with just over 2.2mS of fuel (assuming 1 squirt per cycle) and then look to see whether the highest rpm achievable still allows enough time for the injector to deliver enough fuel at this peak demand level.

kind regards
Marek


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PostPosted: Thu Jun 26, 2014 6:07 pm 
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bit of afternoon fun in the batcave ...

comparing the first dyno run with the last ,there were several runs in between..


Image





Image



and a summary of the data ..


Image


this was with a room temp of 28c and a inlet manifold air temp of 60 c ....bit hot for such low boost . should be around 30 to 40 c on the rd .

last run was a long loaded run to give the time to map it .


happy !


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PostPosted: Wed Jul 02, 2014 7:26 am 
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mapping going well on rd .mpg up from around 24 mpg to 28.4 .running leaner and leaner to find limits .at 17:1 so far on cruise.


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PostPosted: Thu Jul 17, 2014 9:41 am 
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hello chaps , quick update ,

have done about 700 miles so far , playing with 18:1 afr cruise ,and 13.5 on power.(petrol afr's derived from lambda ). had a lot of traffic and hold ups so still at 28 to 29.5 mpg .this is up from 23 to 24 mpg on the single point ring .

I have not played with the fuel shut off on deccel yet, its still at 70%,so maybe some savings there ,alos I have some accel enrichment in it that may not be needed ,so will try reducing that til it gets jerky .

gas temp varies between 60 and 90 c .and inlet air temp beyween 25(amb) and 56c after a good heat soak. I think that sensor is getting more manifold temp ,since it cools on boost .

the car runs closed loop all the time ,and definitely richens up a bit as things get very hot , I think I need to drop the air temp pw a bit too.

all in all very happy , drives basically like a normal untouched stock car ....apart from early morning starts ,where a little throttle needed .

no idle control is being used ,cold rpm 500 ,warm rpm 1000 .275 degr cam.


Robert.


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PostPosted: Fri Nov 07, 2014 6:40 am 
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back once again ...

so finally got the bigger t25 turbo on the dyno ..


i like it !


Image




i went through various steps....


heres a boost log ...pk boost at pk bhp is 10 psi.


Image

firstly tried a multitude of mixtures ,here are a couple...


Image


Image



then a test on ignition timing ..there may be a little more to get here , but im playing it a bit safe ,and remember ,boost rises from 7 to 10 psi but most of the time its between 7.5 and 9.5.



Image


Image


then a comparison between turbo's and over the days progress scaled to show max detail..



Image



Image


lastly power and torque on a 0 scale to show real smoothness levels .


Image


Image


boost log for last runs ...psi bit higher at 10.477psi.boost control seems erratic!



Image


then i had a play with low rpm torque i raised and lowered timing to see what i'd gain .turns out to be around 6 lbs/ft at 1800 ,noice.



Image



phew .lots of runs... 35 in total .. engine stayed cool throughout ,and today i might have a go at economy tuning .. i did an experiment yesterday where i held the car at 75 mph ,and changed throttle opening to replicate cruise vacuum .i did it at 10'' and 5'' hg ,and got 7 bhp and 22 bhp .so that's my range .i plan to vary settings ,and watch injector pulse width ,lower the better for the same bhp .


regards
robert. :-)



oh couple of boring vids...



http://youtu.be/Pi79uPNxbVY



http://youtu.be/eN68ZIlO5Gc


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PostPosted: Fri Nov 07, 2014 6:59 am 
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well heres a fine kettle of fish.

i noticed that it was a little bit difficult to start the other day , and recognised it was due to the resistor pack lowering the amps at the injectors enough to stop them opening in cold 5c weather ,when voltage is lower.

so i made a bypass relay pack , that fed 12v to the injectors only whilst cranking . this worked well.

today it was -2 overnight and around +1c when i tried to start , no joy ,so i bled off the pressure in the injector feed , and cranked the car with lpg off until the injectors started ticking ,then switched on the lpg ,and it fired up fine ,and ran and started from then on .

so i guess i need either more voltage , inj that need less volts to fire up , or less gas pressure . :(

regards robert.


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PostPosted: Mon Feb 22, 2016 8:00 am 
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update :


fixed the cold starting by a) fitting a big powerful new battery .b) shimmed the injector coils so they could not move ,thus giving a bigger kick to the pintle inside .c)cranking then turning on the gas .

all been fine down to -5 so far.



new developments .


head gasket started allowing combustion gases into the waterway on number 1 when on boost .this got to the stage were it pushed the water into the header and starved the vap of heating ,so the thing froze and car stopped .


stripped ,and found the gasket pushed into the waterway on the screen side .fia gasket .

got a genuine payen ,and decided to re do the compression ratio for more economy ..after measuring it with the old fia gasket it was 9.77:1 ,so skimmed head on an old harrison mill ,and now at 10.14:1... will probably run lower boost .


chamber ,after 6 years looked like this ..


Image



pretty clean, and the valves seated with only 30 seconds of grinding by hand ,no recession at all. :)


will be fitting a knock sensor ,with a visual tell tail this time.


lastly , a question ..i have the vap t pieced off the heater pipes ,the engine runs rich at first in cold weather ,and i wonder ,what's the general thinking about t piecing, compared to direct from the block to the vap then to the heater ,for a more direct instant heat up ? what do you do ?

im very excited to see what my higher cr does to economy and boost onset .

regards
robert


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PostPosted: Mon Feb 22, 2016 9:04 am 
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Depends on how the heater regulates the temperature. If, as in my Range Rovers, it is done with flap valves so the matrix has full flow all the time but it is the airflow that is diverted, then series connection is far better. My Classic was in parallel and would freeze the vaporiser within the first 300m on a cold day, the P38 was the same and while that didn't freeze, the heater output was decidedly lukewarm when sitting idling on a cold day. Changing them to series plumbing cured both problems. I suppose it depends which route for the coolant is easiest causing the other to suffer. However, if the heater regulates the temperature by closing off the flow to the matrix, then parallel is your only option unless you want to keep the heater turned off in cold weather.

The Medusa thread on RodnSods has gone a bit quiet again??????

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PostPosted: Mon Feb 22, 2016 9:31 am 
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Thanks Gilbert ,ok i will change it to series ,vap 1st then heater or heater first ?

medusa wise yes its a bummer but i have to get the rest of the batcave finished first to make some income ,and then the astra did its thing too .bah !


Last edited by robertXX on Mon Feb 22, 2016 11:06 am, edited 1 time in total.

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PostPosted: Mon Feb 22, 2016 10:32 am 
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I've plumbed mine to go to vap first as that made the pipework neater but I don't suppose it would make too much difference. As long as both the vap and heater are getting the full flow through them which you won't with them in parallel.

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PostPosted: Mon Feb 22, 2016 1:54 pm 
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There won't be a heater water flow shutoff/control solenoid on an Astra. Worst case scenario would be an on/off vac controlled solenoid when which only activates when heater is set to full cold but I've never seen this type on an Astra either. Indeed at least some of the factory fitted Astras have reducer and matrix piped in series, including on models with aircon.

Whether or not you'll get more flow piped in series than piped in parallel will depend on matrix flow restriction and 'open' flow rate through the heater circuit. I've piped new installs on Astras both ways with little difference either way (sequential installs not starting on gas in cold)... except where the matrix is clogged. Obviously with series piping if the matrix is clogged this will prevent water flowing through the reducer as well, and Vauxhall matrix's can be prone to clogging. I'd try series but only if the heater works really well!

With series flow I dunno whether I'd prefer flow order matrix-reducer or reducer-matrix - reducer-matrix could mean variable heat from the vents (gets colder under load) but will heat the reducer better.

On another thread I mentioned how, after changing the gearbox on my car, I didn't put enough antifreeze in (at first) and was always starting on gas regardless of temp (petrol pump broken).. On a particularly cold morning (during at first) the coolant froze in the reducer, so car ran for seconds then cut out - had to pull my son's car up in front of mine and pipe hot gas to the injectors to get it started, would only run on it's own reducer after the ice blockage had cleared! Then I added more antifreeze and fixed the petrol pump..

Simon

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PostPosted: Mon Feb 22, 2016 6:00 pm 
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cool thanks simon , i am going with vap matrix ,all done now , the heater in this works really well so time will tell.


regards robert


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PostPosted: Mon Feb 29, 2016 4:00 pm 
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well what a fun saga i had getting the thing running well!!!


seemed ok on tickover ,but missing and running on 3 on power and generally cutting onto two on tickover when hot and dropping the throttle .also problem was worse hot and better cold .

so did the usual things , different coil pack ,edis module, plugs checked cam timing , checked compression ,then finally sussed it .

i tried a colourtune on no 1 ,and could see no combustion flame at all , checked spark ,all ok ...


when i had the inlet manifold off to skim the head , i had re tightened the clips on the lpg feed pipes. when running i had noticed a very occasional whistling sound ,

so i had a good look at the pipes ,no 1 cylinder clip was sitting a little far from the manifold , so i took it off ,and looked down the pipe and a tiny 1mm hole looked back at me ... mr numpty had tightened the clip half on and half off the stub ,and it had internally collapsed the pipe. cut off the affected inch of pipe ,and re did it ,and drives perfectly well now .(in fact with its new higher cr and the knock control on it it seems a bit godamn peppy!)



oooof!


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PostPosted: Mon Feb 29, 2016 7:17 pm 
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:lol: Sorted the same kind of prob plenty times Rob! Type of thing that can take some finding sometimes..
http://www.lpgforum.co.uk/viewtopic.php?f=28&t=13861

Simon

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PostPosted: Mon Feb 29, 2016 7:24 pm 
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thanks simon , i followed your link , thank goodness i didn't have such a saga .


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PostPosted: Tue Mar 01, 2016 12:59 pm 
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How's Medusa coming on Rob? How about a Rolls Royce Griffin engine in a street car for the next project? :twisted:

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PostPosted: Wed Mar 02, 2016 8:59 am 
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LPGC wrote:
How's Medusa coming on Rob? How about a Rolls Royce Griffin engine in a street car for the next project? :twisted:

Simon




simon , i wish i could be working on medusa ,however , finances dictated that i get my cave finished toot sweet and get some money in from the dyno and flow bench.


i have just recently found two engines of a unique configuration at my friends place ,that would make a very interesting twin engined car .

they are supercharged two stroke diesels ,commer ts3 engines ,with a well weird cylinder design ,with a piston at either end of the same cylinder ,travelling towards each other .lovely ! nice big wade ro34 blower on each one too.apparently they are super loud lol.


anyrdup , i now have the ceiling up and today start with the paint and then sound proof the walls then paint floor do lighting and done.


regards
robert.


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